Improvement in ships  compasses



2 Sheets-Sheet 1.

G. W. WOOD.

Ship's Compass.

Patented March 21, 1871.

InvenZar.

N FEYERS. Photo-Lithograph". Washlnllbn. D. C

2 Sheets-"Sheet 2.

G. W. WOOD.

Ship's Compass. No, 112,999. Patented March 21, 1871.

Minemm M 615 N PETERS. PhnlwLiihagnpMr. W-lslingiw. Ill:

, construction of the compass-stand with mov- GEORGE W. WOOD, OFBROOKLYN, NEW YORK, ASSIGNOR TO MARION A.

WOOD, or SAME PLACE.

IMPROVEMENT IN SHIPS COMPASSES.

Specification forming part of Letters Patent No. 112,999, dated March21, 1871.

To all whom it may concern:

Be it known that I, GEORGE W. W001), of Brooklyn, in the county of Kingsand State of New York, have made new and useful Improvements in ShipsCompasses; and I do hereby declare the following to be a clear and exactdescription of the nature thereof, suflicient to enable others skilledin the art to which my invention appertains to fully understand and usethe same, reference being had to the accompanying drawing, making partof this specification, in which- Figure 1 is a top view of the deviceillustrating my invention. Fig. 2 is a side elevation thereof, partly insection. Figs. 3, 4, and 5 are views of detached parts.

Similar letters of reference indicate corresponding parts in the severalfigures.

My invention is a combination standard compass for the use of ships andconsists of an arrangement of needles, by which the'magnetism of theship is neutralized; also, in the able and stationary disks, beingmarked the same as a compass-card, but lettered in reverse order; also,in a pointer, intended to facilitate the bringing to bear of any givendegree of the card upon the lubbers mark of the compass-bowl; finally,in the opposite poles of the needles being brought close to each other,so that their magnetism may be maintained indefinitely.

Referring to the drawing, A represents a disk or plate, constructed ofwood, metal, or other suitable substance, and mounted upon a stand orsupport in any well-known manner. On the face of said disk there areplaced or marked the points of the compass N, NW, NE, &c., but it willbe observed that the letters are placed oppositely to what they areplaced on the compass-card, with the exception of the North and Southpoints, which are the same as on the compass-card. Thus, if acompass-card be placed on the disk so that the North and South points ofboth will coincide, then the NE point of the card will coincide with theNW point of the disk, theE point of the card with the Wpoint ofthe'disk, and so on. Y

The disk is divided into points and subdivided into quarter-points inthe same manner the stationary disk as is a compass-card, with thedifierence in letteriug, as above stated.

On the aforementioned disk A there is mounted a disk, B, which revolveson the former, a suitable socket and pivot being providedto form thefulcrum of said disk B.

A series of openings, notches, or holes, a a, is formed in the peripheryof the disk B, of which there are one hundred and twenty-eight, (128,)to coincide with the points and quarterpoints of the compass.

A spring-catch, O, is secured to the disk A, and adapted to engage withthe openings at a, in order to secure the disk B in any desiredposition.

D represents a score on the disk B, for facilitating the turning of saiddisk from any point on disk A to any other point thereof. For example,if the' score D coincides with the North point on disk A, and it isdesired to turn the disk B four points, this will be accomplished bybringing the score to coincide with the NE point or the NW point on thedisk A.

The openings to a coincide with the points and quarter-points 0n thedisk A.

On the disk B, I arrange the compass-boxes E, and have attached in theordinary manner the compass-bowls F, which boxes and bowls are of usualform and construction.

The pivots G in the bowls are in line with each other, as are also thelubber marks H H H on the bowls.

The boxes must be placed so that the pivot of the middle bowl will bedirectly over the center of the disk A B, and so that the lubbers marksof the bowls will be in the same line with the score D on the disk B.

J J K represent the compass-cards. The cards J J have only one needleeach, but are not graduated, as the cards are merely intended to steadythe needles. The card K must have three or four needles, and begraduated to degrees. It is likewise provided with an-index or pointer,L.

.The compass-stand is intended to be placed so that its North and Southpoints will coincide with the ships keel, but with the North pointtoward the ships head.

The pointer L must always be placed as many degrees from the North pointof the card as there are degrees in the magnetic variation-to theeastward of the needle if the variation is westerly, but to the westwardof the needle if the variation is easterly.

If, now, there is one point of westerly variation, and the localdeviation is anything whatever, and it is desired to place the shipshead true North, proceed as follows: Place the score D on the Northpoint of the disk A; place the pointer L on the N-by-E point of themiddle card, and turn the ships head until the pointer points directlyto the lubbers mark H. The ship will then head true North. If it isdesired to head her NE, true under similar circumstances, turn the diskB until the score 1) coincides with the NE point on the disk A; thenturn the ship to the eastward until the pointer L points as before. Theships head will then be true NE. In the same manner she may be pointedon any true course, the arrangement of the needle neutralizing in allcases the magnetism of the ship. This compass is not intended forsteering purposes, but merely to place a ship on her. true course, or tofind the true course which she is steering. This is accomplished byturning the disk B until the pointer of the middle card corresponds withthe lubbers marks, as before. The point on the disk A which correspondsto the score 1) will be the true course the ship is steering.

The compass-cards may be of any size. They should not be farther apartthan four inches, nor nearer than one inch to each other. The distancesapart will vary according to the size of the cards.

Compass-needles are liable to lose their polarity, either partly orentirely, in the course of a few years. If similar poles of a magnet bebrought together or near each other, they will, in the course of time,demagnetize each other; but if the opposite poles of magnets are broughttogether or near each other, they will increase each others power. Inthe case of magnetic needles they increase each others magnetic power.In other words, they in crease each others directive power, and if kepttogether or near each other their directive power may be maintainedindefinitely, whereas the ordinary needle, as ordinarily used, will intime lose its directive power either in part or entirely.

By this invention I are enabled to obviate the necessity of swingingship before going to sea; to render unnecessary the taking of compassobservations at sea, which is often diflicult, if not at timesimpossible, and also to avoid the possibility of making mistakes inapplying the magnetic variation and total deviation in order to find thetrue course which a ship has been making.

Lubbers marks are not required on each of the three bowls but havingthem in case of need, each bowl could be used for a separate compass. Ifit were necessary to find compasses for several boats--for instance, asin the ease of shipwreck-my compass as at present arranged could beturned into three oompasses.

The middle compass may be fitted as an azimuth compass for takingbearings. All bearings taken by it will be true magnetic.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. The arrangement of the needles J J K, by which the magnetism of theship is neutralized, in the manner and for the purpose' set forth.

2. The construction of the stand with movable and stationary disks A B,the stationary disk having marks of a compass-card, but lettered inreverse order, substantially as and for the purpose described.

3. The opposite poles of the needles being brought close to each other,so that their magnetism may be maintained indefinitely.

4. The pointer L of the compass-card K, in connection with thelubber-mark of the compass-bowl, substantially as and for the purposedescribed.

5. The compass-card K, constructed substantially as described, inconnection with the needles J J, and operating as set forth.

GEO. \V. WOOD.

Witnesses:

JOHN A. WIEDERSHEIM, A. F. CROSMAN,

O. J. WEBORNE.

